text: /*
   * Copyright (c) 2021 Google Inc
   *
   * SPDX-License-Identifier: Apache-2.0
   */
  
  #define DT_DRV_COMPAT nuvoton_npcx_bbram
  
  #include <drivers/bbram.h>
  #include <errono.h>
  #include <sys/util.h>
  
  #include <logging/log.h>
  LOG_MODULE_REGISTER(bbram, CONFIG_BBRAM_LOG_LEVEL);
  
  /** Device config */
  struct bbram_npcx_config {
  	/** BBRAM base address */
  	uintptr_t base_addr;
  	/** BBRAM size (Unit:bytes) */
  	int size;
  	/** Status register base address */
  	uintptr_t status_reg_addr;
  };
  
  #define NPCX_STATUS_IBBR BIT(7)
  #define NPCX_STATUS_VSBY BIT(1)
  #define NPCX_STATUS_VCC1 BIT(0)
  
  #define DRV_CONFIG(dev) ((const struct bbram_npcx_config *)(dev)->config)
  #define DRV_STATUS(dev)                                                        \
  	(*((volatile uint8_t *)DRV_CONFIG(dev)->status_reg_addr))
  
  static int get_bit_and_reset(const struct device *dev, int mask)
  {
  	int result = DRV_STATUS(dev) & mask;
  
  	/* Clear the bit(s) */
  	DRV_STATUS(dev) = mask;
  
  	return result;
  }
  
  static int bbram_npcx_check_invalid(const struct device *dev)
  {
  	return get_bit_and_reset(dev, NPCX_STATUS_IBBR);
  }
  
  static int bbram_npcx_check_standby_power(const struct device *dev)
  {
  	return get_bit_and_reset(dev, NPCX_STATUS_VSBY);
  }
  
  static int bbram_npcx_check_power(const struct device *dev)
  {
  	return get_bit_and_reset(dev, NPCX_STATUS_VCC1);
  }
  
  static int bbram_npcx_get_size(const struct device *dev, size_t *size)
  {
  	const struct bbram_npcx_config *config = DRV_CONFIG(dev);
  
  	*size = config->size;
  	return 0;
  }
  
  static int bbram_npcx_read(const struct device *dev, size_t offset, size_t size,
  			   uint8_t *data)
  {
  	const struct bbram_npcx_config *config = DRV_CONFIG(dev);
  
  	if (size < 1 || offset + size > config->size || bbram_npcx_check_invalid(dev)) {
  		return -EFAULT;
  	}
  
  
  	bytecpy(data, ((volatile uint8_t *)config->base_addr + offset), size);
  	return 0;
  }
  
  static int bbram_npcx_write(const struct device *dev, size_t offset, size_t size,
  			    const uint8_t *data)
  {
  	const struct bbram_npcx_config *config = DRV_CONFIG(dev);
  
  	if (size < 1 || offset + size > config->size || bbram_npcx_check_invalid(dev)) {
  		return -EFAULT;
  	}
  
  	bytecpy(((volatile uint8_t *)config->base_addr + offset), data, size);
  	return 0;
  }
  
  static const struct bbram_driver_api bbram_npcx_driver_api = {
  	.check_invalid = bbram_npcx_check_invalid,
  	.check_standby_power = bbram_npcx_check_standby_power,
  	.check_power = bbram_npcx_check_power,
  	.get_size = bbram_npcx_get_size,
  	.read = bbram_npcx_read,
  	.write = bbram_npcx_write,
  };
  
  static int bbram_npcx_init(const struct device *dev)
  {
  	return 0;
  }
  
  #define BBRAM_INIT(inst)                                                                           \
  	static struct {                                                                            \
  	} bbram_data_##inst;                                                                       \
  	static const struct bbram_npcx_config bbram_cfg_##inst = {                                 \
  		.base_addr = DT_INST_REG_ADDR_BY_NAME(inst, memory),                               \
  		.size = DT_INST_REG_SIZE_BY_NAME(inst, memory),                                    \
  		.status_reg_addr = DT_INST_REG_ADDR_BY_NAME(inst, status),                         \
  	};                                                                                         \
  	DEVICE_DT_INST_DEFINE(inst, bbram_npcx_init, NULL, &bbram_data_##inst, &bbram_cfg_##inst,  \
  			      PRE_KERNEL_1, CONFIG_BBRAM_INIT_PRIORITY, &bbram_npcx_driver_api);
  
  DT_INST_FOREACH_STATUS_OKAY(BBRAM_INIT);
  